Surface illuminator and liquid crystal display having the same

Abstract

The invention provides a surface illuminator capable of achieving high display quality by employing an array of discrete light sources constituted by a plurality of LEDs and a liquid crystal display having the same. The surface illuminator includes an LED module which is a plurality of LEDs alternately and discretely provided along a light entrance surface and a color irregularity correcting resistor which is connected in parallel with a predetermined LED at an end of the LED module and which provides a bypass for a current supplied to the LED.

1. A surface illuminator comprising:
 a light exit region which extends in the shape of a plane and from which light exits; 
 a light guide region arranged to guide light to the light exit region; 
 a light entrance surface through which light enters the light guide region; 
 a reflective surface on a side portion of the light guide region extending from an end of the light entrance surface and reflecting light in the light guide region; 
 an LED module including a plurality of LEDs alternately and discretely provided along the light entrance surface, the LEDs including different spectral characteristics; and 
 a color irregularity correcting resistor disposed within the LED module and connected in parallel with only a predetermined one or more the LEDs at an end of the LED module located on a side of the reflective surface such that the color irregularity correcting resistor reduces color irregularities adjacent to an end of the reflective surface; 
 wherein color irregularities are reduced when displaying white by matching the luminance ratios of beams of light in primary colors from the LEDs and making the peripheral luminance ratios of the colors uniform. 
 
   
   
     2. A surface illuminator according to  claim 1 , wherein the color irregularity correcting resistor is a variable resistor. 
   
   
     3. A surface illuminator according to  claim 1 , wherein a switch is provided in series with the color irregularity correcting resistor. 
   
   
     4. A surface illuminator according to  claim 1 , comprising a second color irregularity correcting resistor connected in series with the predetermined LED. 
   
   
     5. A surface illuminator according to  claim 1 , wherein the predetermined LED is at least one of three LEDs provided at an end of the LED module located on the side of the reflective surface. 
   
   
     6. A surface illuminator according to  claim 1 , wherein the predetermined LEDs are at least two among three LEDs provided at an end of the LED module located on the side of the reflective surface. 
   
   
     7. A surface illuminator according to  claim 1 , wherein the predetermined LEDs are three LEDs or LEDs in a quantity that is a multiple of three, provided at an end of the LED module located on the side of the reflective surface. 
   
   
     8. A surface illuminator according to  claim 1 , wherein the predetermined LEDs are four LEDs or LEDs in a quantity that is a multiple of four having three types of spectral characteristics, provided at an end of the LED module located on the side of the reflective surface. 
   
   
     9. A surface illuminator according to  claim 1 , wherein the predetermined LEDs are four LEDs or LEDs in a quantity that is a multiple of four having four types of spectral characteristics, provided at an end of the LED module located on the side of the reflective surface. 
   
   
     10. A surface illuminator according to  claim 1 , wherein four of the LEDs at the end of the LED module on the side of the reflective surface are arranged in the order of green, red, blue, and green from the end. 
   
   
     11. A surface illuminator according to  claim 1 , wherein four of the LEDs at the end of the LED module on the side of the reflective surface are arranged in the order of green, blue, red, and green from the end. 
   
   
     12. A surface illuminator according to  claim 1 , wherein the LEDs are arranged in the same order of colors from both ends of the reflective surface. 
   
   
     13. A surface illuminator according to  claim 1 , wherein optical sensors arranged to control luminance and chromaticity are provided at four corners and the center of a back side or front side of the light exit region. 
   
   
     14. A surface illuminator according to  claim 1 , wherein the LED module is provided on one side of the light entrance surface. 
   
   
     15. A surface illuminator according to  claim 1 , comprising a housing defined by a sheet of metal or a mold having an adjusting hole that allows the color irregularity correcting resistor to be adjusted from outside. 
   
   
     16. A liquid crystal display having a liquid crystal sealed between a pair of substrates provided opposite to each other, the display comprising a surface illuminator according to  claim 1 .